Pumping liquids and fluids, such as oils and distillates produced from oil wells, presents a problem as these fluids frequently contain entrained contaminating materials such as sand, grit and the like. The pumping of such fluids results in the entrained abrasive materials coming into contact with the pump elements, and in particular, the pump surface elements as well as the pump shaft bearings and seals. Consequently, pumps in service for pumping such liquids require frequent maintenance and repair as a result of premature wear and failure after a relatively short period of use. Pumps employing meshing gears are often used to pump such fluids. Such gear pumps typically include single-helical gears that in operation, as a result of contact between the meshed gear teeth, create axial thrust forces along the pump shafts, which causes an increase in end plate wear.
To address these problems, pumps include modular designs to increase the serviceability of the pump and reduce overall pump downtime, include wear plates to take the axial thrust forces along the pump shafts to reduce end plate wear, and include bearing assemblies and seal arrangements that operate to reduce the tendency of contaminated fluid contact with the bearing assemblies.
Another problem encountered is leaking of fluid externally of the pump due to a worn dynamic packing seal that is used to provide a seal between the protruding end of the pump driving shaft and the pump housing or end plate. Heretofore, servicing and replacement of the packing seal required the pump to be shutdown.
Another problem encountered is the formation of area of high pressurized fluid at the end of a pump shaft created during the pump operation. The pressurized fluid creates an axially loading on the pump shaft causing the pump shaft to be urged towards the opposite end resulting in an increase of pump component wear.
Accordingly, there is a need for a pump design used to pump fluids contaminated with abrasives that has an increased service life and an improved serviceability and that overcomes the limitations associated with conventional pump designs heretofore.